your source avi is probably the issue. it has to do with the encoding. this is especially likely if it's a downloaded file
you'd probably have to demux and manually align the audio and video, but i don't know how that works. it's been addressed before. you can try a search while you're waiting for more input and you may be able to find something along the same lines as your question.
also, you do not burn with dvd shrink. that is impossible since shrink has never had a burning engine.